jamming rods into a Rad! I hope they were soft nylon or similar.
Radiators have a way of lying to you. You can run a hose pipe (Water) thru them, it runs clear, you think that you have cleared all the gunk from them, in fact you may have just cleared a passageway through the gunk...the rad may still be gunked up. (Same principle applies to Domestic central heating too).
To check a rad is working, you need to remove the front grille of the car, so you can feel the rad. If there is cold spots, it's gunked. There of course should be cooler spots, that's what the rad is for, takes in hot gives out cooler...but the gunked up areas remain rather cool.
I have cleaned out the system with cleaning solvents, added to the coolant. Thing is, they do not dissolve the stuff, just loosen it, and lumps of gunk now get cornered in the thermostat house or the heater valves..or any other corner that is going to be harder to fix!
One day, I will try a Domestic Central heating cleaner, see if that fares any better.